Laminated Mesostructures in All‐Solid‐State Battery Composite Electrodes via a Rolling‐Folding Strategy

ABSTRACT

In all‐solid‐state batteries (ASSBs), the solid‐state electrolyte (SSE) has a generally higher density, making it challenging to balance cell‐level energy density and rate capability in ASSB composite electrodes. For ASSB composite electrodes, it is necessary to reduce Li ⁺ pathway tortuosity with a limited SSE volume fraction via mesostructural engineering. Previously reported mesostructural methods relied mainly on pore‐forming and liquid‐infiltrating, which are materials‐limited and face issues such as volume shrinkage. In this work, we propose a mechanical method, forming laminated low‐tortuosity Li ⁺ pathways via a rolling‐folding process. This method is highly adjustable, enabling systematic control over ASSB composite electrode mesostructure with potential applicability to different material systems. As a demonstration, we use a LiCoO ₂ (LCO) cathode and a Li ₆ PS ₅ Cl (LPSC) SSE to fabricate ASSB cells. Our cells achieve high active material loadings up to 31 mg cm ⁻² , delivering 2.2 and 5.1 mAh cm ⁻² discharge capacities at 12.5 and 0.6 mA cm ⁻² current densities, and maintain 93% capacity retention (to 3.9 mAh cm ⁻² ) after 500 cycles at 3.1 mA cm ⁻² . This work demonstrates the rolling‐folding process as a versatile mesostructure engineering method for designing practical high‐performance ASSB electrodes with high areal capacity.